This invention relates generally to a method and apparatus for use in orthopedic surgery and, more particularly, to a method and apparatus for providing a modular acetabular prosthesis having various modular attachment components for use during an orthopedic surgical procedure.
A natural hip joint may undergo degenerative changes due to a variety of etiologies. When these degenerative changes become so far advanced and irreversible, it may ultimately become necessary to replace a natural hip joint with a prosthetic hip. When implantation of such a hip joint prosthesis becomes necessary, the head of the natural femur is first resected and a cavity is created within the intramedullary canal of the host femur for accepting the hip prosthesis. The hip prosthesis may be inserted and supported within the host femur by cementing the hip prosthesis within the host femur. Alternatively, the hip prosthesis may be impacted into the host femur so that it is snugly fit and supported by the host femur. If the acetabulum also needs repair, all remnants of articular cartilage are generally removed from the acetabulum and an acetabular prosthesis which will accommodate the head or ball of the hip prosthesis is affixed to the acetabulum. The acetabular prosthesis is affixed to the acetabulum by means of cement, screws or other appropriate fixation means.
Due to any number of reasons, however, a small portion of patients that undergo such orthopedic surgical procedures may require subsequent revision surgery to replace the prosthetic device with a new prosthetic device generally referred to as a revision prosthesis. One example of such a device is generally known as a protrusio cage.
In this regard, a revision acetabular prosthesis will generally include additional mounting points, such as integral extension members or hooks that provide additional stability for the revision acetabular prosthesis. These additional mounting points are generally required due to additional bone loss or defects exhibited at the acetabulum, such as collar/rim defects or pelvic discontinuity defects.
Various types of revision acetabular prostheses are currently available and different surgeons prefer different types of revision acetabular prostheses. Some surgeons prefer to use what is known as an ilium flange that is formed integral with the acetabular prosthesis and enables further securement of the acetabular prosthesis in the ilium region of the pelvis. Other surgeons prefer to use what is known as an obturator hook that is able to provide inferior fixation of the acetabular prosthesis by engaging the obturator foramen which is a large aperture adjacent the acetabulum. Because of this, a hospital must maintain a large inventory of different revision acetabular cups to meet the various surgeons"" preferences. Moreover, the surgeon will generally have to have several revision acetabular cups available during surgery to account for any type of condition that may arise during the surgical procedure. This increased inventory of prosthetic devices increases the overall hospital costs and inventory control. Furthermore, by requiring the multiple revision acetabular cups to be available during the surgical procedure, multiple prosthetic devices must be sterilized prior to the surgical procedure, thereby increasing the surgical time, cost and complexity.
As previously noted, during hip revision procedures, surgeons often encounter significant defects due to osteolysis at the acetabular implant site or due to the removal of bone tissue that has become attached to the removed acetabular implant. These defects are usually filled with bulk bone allograft, bone cement, or morselized bone graft. Each material type raises it""s own set of concerns.
With respect to bulk bone allograft, many doubts exist as to whether significant portions of a bulk allograft actually become viable over time. Dead allograft may not provide long term structural support. Additionally, higher infection rates are sometimes connected to the use of bulk allograft. Finally, bulk allograft is also expensive and sometimes unavailable or difficult to obtain.
With respect to bone cement, when defects are filled with bone cement, subsequent revision procedures may be made more difficult because there is even less bone tissue to work with.
With respect to morselized bone graft, this has become the material of choice; however, it may not provide significant structural support. Motion of the acetabular implant is of real concern. For example, motion can prevent bone tissue from infiltrating the porous surface of the acetabular implant and thus can place too much load on a thin walled acetabular implant and screws, potentially causing them to fail. Additionally, morselized bone graft is very expensive and is sometimes unavailable or difficult to obtain.
What is needed then is a method and apparatus for providing a modular acetabular prosthesis having various modular attachment components for use during an orthopedic surgical procedure. This will, in turn, provide more surgical flexibility during implantation of the acetabular prosthesis, provide the surgeon with a variety of surgical options at the time of the surgical procedure, provide a universal acetabular cup that can be configured for use in many circumstances, reduce hospital inventory and inventory tracking requirements, and reduce the overall surgical time, cost and complexity.
In accordance with a first embodiment of the present invention, an acetabular prosthesis for implantation in an acetabulum and surrounding pelvis is provided, the acetabular prosthesis comprising: (1) an acetabular cup having a substantially concave inner surface and a substantially convex outer surface, the outer surface operable to be received in the acetabulum; (2) an area defining a receptacle located in the outer surface of the acetabular cup; (3) a spacer member having an appendage formed on a surface thereof for mating engagement with the receptacle, wherein the spacer member is disposed between the outer surface of the acetabular cup and the acetabulum; and (4) an attachment member integral with the acetabular cup for fastening to a surface of the pelvis.
In accordance with a second embodiment of the present invention, an acetabular prosthesis for implantation in an acetabulum and surrounding pelvis is provided, the acetabular prosthesis comprising: (1) an acetabular cup having a substantially concave inner surface and a substantially convex outer surface, the outer surface operable to be received in the acetabulum; (2) an attachment member integral with the acetabular cup for fastening to a surface of the pelvis; and (3) a spacer member adjacent to the attachment member, wherein the spacer member is disposed between the attachment member and the surface of the pelvis.
In accordance with a third embodiment of the present invention, a method for implanting an acetabular prosthesis in an acetabulum and surrounding pelvis is provided, comprising: (1) providing an acetabular cup having a substantially concave inner surface and a substantially convex outer surface, the outer surface operable to be received in the acetabulum, the outer surface of the acetabulum cup having an area defining a receptacle located therein, the acetabular cup having an attachment member integral therewith for fastening to a surface of the pelvis; (2) providing a spacer member having an appendage formed on a surface thereof for mating engagement with the receptacle; (3) securing the spacer member to the outer surface of the acetabular cup; (4) engaging the outer surface of acetabular cup with the acetabulum such that the spacer member is disposed between the outer surface of the acetabular cup and the acetabulum; (5) securing the acetabular cup to the acetabulum; and (6) securing the attachment member to the surface of the pelvis.
In accordance with a fourth embodiment of the present invention, a method for implanting an acetabular prosthesis in an acetabulum and surrounding pelvis is provided, comprising: (1) providing an acetabular cup having a substantially concave inner surface and a substantially convex outer surface, the outer surface operable to be received in the acetabulum, the acetabular cup having an attachment member integral with the acetabular cup for fastening to a surface of the pelvis; (2) providing a spacer member adjacent to the attachment member; (3) securing the spacer member to the attachment member; (4) engaging the outer surface of acetabular cup with the acetabulum such that the spacer member is disposed between the attachment member and the surface of the pelvis; (5) securing the acetabular cup to the acetabulum; and (6) securing the spacer member and the attachment member to the surface of the pelvis.
A more complete appreciation of the present invention and its scope can be obtained from the following detailed description of the invention, the drawings and the appended claims.